Recreational and utility trailers often are towed by automobiles, pick-up trucks, and other vehicles, such as recreational vehicles. The trailers are provided with an electric braking system that includes a pair of brake shoes (for a two wheeled trailer) which are actuated by a well known electromagnet-actuated lever device to apply a braking force to the drums of the trailer wheels. Generally, the braking force applied by the brake shoes against the wheel drums is proportional to the electric current supplied to the wire coils of the electromagnets.
Electronic brake controllers are available which include a sensing device that generates a brake control signal corresponding to the desired magnitude of braking force to be applied to the towed vehicle. For example, a pendulum is used in some electronic brake controllers to sense deceleration of the towing vehicle upon braking and generate a brake control signal proportional to movement of the pendulum, for example, as described in U.S. Pat. No. 4,721,344.
Such electronic brake controllers usually include an analog pulse width modulator which receives the brake control signal from the sensing device. The pulse width modulator is responsive to the brake control signal to generate an output signal that has constant frequency pulse train with the duty cycle of the pulse train varied in proportion to the magnitude of the brake control signal from the sensing device. An output stage of the controller is electrically connected to the output of the pulse width modulator. The output stage can have multiple power transistors which are connected between the towing vehicle power supply and the towed vehicle brake electromagnets and which function as an electronic switch for supplying electric current to the coils of the electromagnets. The output is responsive to the pulse width modulator output signal to switch the power transistors between conducting and nonconducting "on"/"off" states. As the transistors are so switched, the brake current is divided into a series of pulses. The power supplied to the towed vehicle electromagnets and the resulting magnitude of braking are directly proportional to the duty cycle of the output signal of the pulse width modulator.
An object of the present invention is to provide an electronic brake controller for controlling electric brakes of a towed vehicle in a manner to provide the driver of the towing vehicle with improved control over braking force applied to the wheels of the towed vehicle.
Another object of the present invention is to provide an electronic brake controller for controlling electric brakes of a towed vehicle in a manner to provide a braking force to the wheels of the towed vehicle that is proportional to the braking force applied by the driver to the brake pedal of the towing vehicle.
Still another object of the present invention is to provide an electronic brake controller for controlling electric actuated brakes of a towed vehicle with braking force to the trailer brakes controlled in response to feedback provided by a resistive brake pedal pad sensor that senses the braking force applied by the driver of the towing vehicle.
A further object of the present invention is to provide an electronic brake controller having a main electronic control unit hard wired to the vehicle electrical system and a remote driver-operable manual control unit tethered to the main electronic control unit and positioned at a desired driver-selected location in the towing vehicle to facilitate actuation by the driver of the towing vehicle.